Current limiters are needed in a variety of scenarios, for ensuring that current flowing through a component does not exceed a boundary condition such as a peak current or a minimum current. One example application is to limit the current flowing through an energy storage element in a switched mode power supply (SMPS) or other circuit that applies a varying current to a circuit component.
Limitation of current involves detecting the current through or at a component and then modifying the configuration or operation of a circuit to decouple the component from the source that is supplying the current. However, there is a time delay between detecting that a given current threshold has been met or exceeded, and then decoupling the component from the current source. This delay arises from factors including the time taken for the detection circuitry and switching circuitry to operate. in cases where the component is an inductor, delays can also arise due to limitations which are placed on how rapidly the voltage bias can be modified across the inductor.
These delays result in an excessive build-up of current in the component and therefore can result in various undesired effects, such as errors in the operation of or causing damage to the circuit of which it forms a part. For example, the current overshoot in an inductor of a SMPS circuit can result in exceeding the saturation current of this inductor.